U1565 – Communication Bus Fault.

The ODBII code U1565 indicates a communication bus fault, meaning there is a problem with the data exchange between various electronic control units (ECUs) in the vehicle.

The severity of ODBII code U1565 Communication Bus Fault is moderate.

Common Causes For: U1564 U1564: “Module Communication Failure”

• Faulty wiring or connectors in the communication bus.
• Malfunctioning control modules.
• Corroded or damaged terminals.
• Short circuits in the communication lines.
• Open circuits in the communication lines.
• Interference from aftermarket devices.
• Software issues or bugs in the control modules.
• Low battery voltage or poor power supply.

Common misdiagnosis for U1565 Communication Bus Fault.

• Faulty ABS module
• Defective body control module (BCM)
• Malfunctioning engine control module (ECM)
• Wiring issues or shorts in the communication lines
• Faulty instrument cluster
• Bad ground connections
• Incorrectly installed aftermarket accessories
• Failed transmission control module (TCM)

Common Troubleshooting Steps

The OBD-II code U1565 indicates a communication bus fault, which typically means there is an issue with the communication between various modules in the vehicle’s network. Here are some common troubleshooting steps to diagnose and resolve this issue:

• Check for Additional Codes: Use an OBD-II scanner to check for any other trouble codes that may be present. Sometimes, multiple codes can provide more context for the issue.
• Inspect Wiring and Connectors:
• Visually inspect the wiring and connectors associated with the communication bus (CAN bus, LIN bus, etc.) for any signs of damage, corrosion, or loose connections.
• Pay special attention to the connectors at the modules involved in the communication.
• Check for Short Circuits:
• Use a multimeter to check for short circuits in the wiring. Look for continuity between the communication wires and ground or power sources.
• Test Modules:
• If you suspect a specific module is causing the issue, you can test it by disconnecting it and checking if the code persists. If the code clears, the module may be faulty.
• Reconnect the module and check for proper operation.
• Inspect the CAN Bus:
• Use an oscilloscope or a CAN bus analyzer to check the signal integrity on the CAN bus. Look for proper voltage levels and signal patterns.
• Ensure that the termination resistors are present and functioning correctly (typically 120 ohms at each end of the bus).
• Check for Interference:
• Look for any aftermarket devices or modifications that may be interfering with the communication bus. This includes alarms, stereo systems, or other electronic devices.
• Battery and Ground Connections:
• Ensure that the vehicle’s battery is in good condition and that all ground connections are clean and secure. Poor grounding can lead to communication issues.
• Software Updates:
• Check if there are any software updates available for the vehicle’s modules. Sometimes, manufacturers release updates to fix communication issues.
• Clear Codes and Test Drive:
• After performing the above checks and repairs, clear the trouble codes and take the vehicle for a test drive to see if the code returns.
• Consult Service Manual:
• Refer to the vehicle’s service manual for specific diagnostic procedures related to the U1565 code and the communication bus system. 1
• Professional Diagnosis:
• If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or dealership for further diagnosis, as they may have specialized tools and knowledge to address complex communication issues. By following these steps, you should be able to identify and resolve the underlying cause of the U1565 communication bus fault.